The brain receives more information that it can simultaneously fully process. The means by which th brain selects which information to process is called attention. For example, while reading this absract you are probably attending to the words on this page and do not feel your foot in your left shoe, bt now you are most certainly aware of it. Prior studies from our and other laboratories have revealed tha injury to the brain as well as aging can alter the means by which we spatially allocate our attention, butmost of these studies have studied the allocation of right versus left spatial attention and few have studid vertical attention. In a pilot study, we found that healthy subjects appear to have an upward attenional bias and it appears that this bias is primarily mediated by the right hemisphere. One of our first oals is to learn what neuropsychological factors may influence this bias. For example, the right hemisphere appears to be dominant for mediating global attention and the lef, focal attention. If we alter attentional demands (global versus focal) by presenting solid versus charactr vertical lines what will happen to this upward bias? Further, we attend more to that which we see frst and since we often scan from top to bottom, this scanning direction may influence the allocation ofvertical attention. To learn the influence of scanning, we will have participants scan solid lines from top o bottom or bottom to top and bisect the lines. Many studies have revealed that with aging there is a reduction of right hemispheric function and tis age related decrement may influence the spatial allocation of attention. For example, young people havea left hemispatial bias that decreases or even reverses with aging and another goal of our study is to lean if with aging there is a decreased upward attentional bias. We will test this hypothesis by having oldr versus younger participants perform vertical line bisections. We have reported that bilateral strokes of the bottom (ventral) portion of the temporal-occipital lbes cause a decrease in upward attention and now we want to learn if unilateral right (versus left) hemispher strokes can induce an alteration of vertical attentional bias, and if bottom (ventral) lesions caus different changes compared to more top (dorsal) parietal-occipital lesions. We will also place thes vertical lines to the left and right of the midsagittal plane to learn if there is an interaction btween hemispace and lesion locus. Performances will be compared to age-matched controls assessed in the aging study. Alteration of spatial attention can be a major cause of disability. There are now several rehabilittion methods that can help to correct horizontal (right-left) disorders of spatial attention and these culd be modified to treat disorders of vertical attention, but first we must learn the types of disorders ad the neurological mechanisms and these are the goals of this proposal.